Nonwoven fabrics and their manufacture have been the subject of extensive development resulting in a wide variety of materials for numerous applications. For example, nonwovens of light basis weight and open structure are used in personal care items such as disposable diapers as liner fabrics that provide dry skin contact but readily transmit fluids to more absorbent materials which may also be nonwovens of a different composition and/or structure. Nonwovens of heavier weights may be designed with pore structures making them suitable for filtration, absorbent and barrier applications such as wrappers for items to be sterilized, wipers or protective garments for medical, veterinary or industrial uses. Even heavier weight nonwovens have been developed for recreational, agricultural and construction uses. These are but a few of the practically limitless examples of types of nonwovens and their uses that will be known to those skilled in the art who will also recognize that new nonwovens and uses are constantly being identified. There have also been developed different ways and equipment to make nonwovens having desired structures and compositions suitable for these uses. Examples of such processes include spunbonding, meltblowing, carding, and others which will be described in greater detail below. The present invention has general applicability to equipment and processes generally of the spunbond type as will be apparent to one skilled in the art.
Spunbond processes generally require large amounts of a fluid such as air that is used for quenching the molten filaments and for drawing and attenuating the filaments for increased strength. This fluid not only represents a cost, but it must be carefully controlled to avoid deleterious effects on the filaments and the resulting nonwoven web. While many advancements have been made in spunbonding processes and equipment, improved web uniformity, strength, tactile and appearance properties with higher efficiency remain sought-after goals.